Step 1

Combine all ingredients in a large stockpot. Add water to fill. Bring to a boil over high heat, skim any foam that comes to the top, and reduce heat to low. Simmer, partially covered, skimming the surface as necessary for at least 4 hours. Top with water occasionally if necessary. Strain and season very conservatively with salt.

Step 2

Cool, and transfer to containers. Store in the refrigerator for use within 1 week, or in the freezer for use within 6 months.